A group of dissident Soviet writers whose works are banned in the Soviet Union had dinner tonight at the downtown Moscow restaurant with the American publishers who have been instrumental in bringing the writers' works to a world public.

The dinner was a historic event int the tortured history of modern dissident Russian literature - an open meeting in a public place with members of the press in attendance. It was a far cry from the usual way this handful of suppressed authors meet with the occasional Western book editor or publisher who visits here - in painfully and carefully arranged sessions in cramped Moscow apartments, in which the atmosphere of tension cannot be shut out by a locked door. The notion of possible trouble frequently hovers as close as the sidewalk outside, where secret police sometimes keep ostentatious vigil.

But the appearances tonight were far different, with Rowkin ETAOIN ETA Harper and Row, Winthrop Knowlton, serving as host for a danquet of more than two dozen, including a number of dissident writers and their spouses.

The writers included Roy Medvedev, Vladimir Voinovitch, Lev Kopelev, Rya Orlova and Alexander Sinoviev, Bulat Okudzhava, a popular folk singer ans songwriter, also attended. His career has experienced periods of disfavor.

For many of the writers, it was a rare public gathering together; several had not seen or heard from one another in some months. Most live under conditions hard to comprehend in the West - their writing published in foreign lands and foreign tongues, their reputations shattered, their official jobs long gone. They live in part sustained by what they hear from Western radio stations and Western magazines and articles brought to them by travelers and friends, and they seldom if ever actually meet face-to-face with the businessmen who publish their works.

So, to the strains of Georgian music wafting up from a dining room below, the dissidents and the publishers gathered for food and drink and kind words. The private dining room on the second floor of the Aragvi Restaurant, overlooking Gorki Street a few blocks from the Kremli, glowed.

Knowlton, the Kopelev and Medvedev got to their feet to speak of the need for international understanding, of their abiding respect for the power of words, and of the need for "peace and progress," the slogan Soviet officials have given the book fair that opened here this week.

Knowlton, who had just arrived from New York, announced that a special shipment of his firm's books - including works by authors who are also suppressed here such as Alexander Solzhenitsyn, Andrei Amalrik, Svetlana Alliluyeva and Joseph Brodsky - never reached the fair.

"We think these books have been censored, and so add them to the list of censored books at the fair," Knowlton said. Nine books published by American firms or universities and five catalogs have been impounded at the fair by customs officials.The publishers concerned have protested and are trying to get the bookds released, so far without success.

Knowlton is chairman of the Committee on Freedom to Publish of the American Association of Publishers. Last month the committee urged U.S. firms exhibiting at the Moscow fair to take a strong stand on behalf of the dissident writers and others who have come under official censure or imprisonment, such as some human-rights activists.

He said he hopes to compile a list of all books thought or known to have been impounded here and withheld from Russian fairgoers. A special exhibit of these works will be set up at the approaching Frankfurt book fair, one of the world's largest.